Gas is one of the main coal mining disaster factors in China. Disasters such as the explosion of coal dust, coal and gas outburst, etc. seriously threaten the safety of coal mines in China. Because of the variety of disaster factors and great governance difficulties, mine gas has always been a top priority and difficulty for the security administrative work of the coal mines in China. At present, the current situation of coal mine safety in China is that: coal mine gas explodes, coal and gas outburst becomes more and more serious and the risk is thus increased. The coal mines in China are all fiery mines, gas disaster has become a main constraint on the safety of coal production and coal industry development. According to national coal mine accident statistics in 2015, there were 71 large and medium-sized mine accidents, wherein 21 accidents were related to gas, accounting for 29.6% of the total mine accidents. The number of casualties in gas accidents accounted for 42.5% of the total casualties. At present, the gas alarms used in coal mines are stand-alone gas alarms, because of the huge sizes of the gas alarms, they are sparsely installed, thus they cannot monitor all the areas effectively.
A solution which combines the gas alarm and the head lamp cap is disclosed in the prior art. For example, a Chinese patent application with the application number of CN 105042545 A, discloses a head lamp cap comprising a head lamp cap body and a head lamp. The head lamp comprises a lamp holder and a lamp body connected to the lamp holder. And the head lamp is fixed on the top surface of the head lamp cap body, wherein the head lamp body is provided with a methane alarm device. Although this design structure can make every user of the head lamp a gas concentration monitor, because the head lamp is fixed on the top surface of the head lamp cap body, it potentially increases the weight of the cap. Furthermore, with the head lamp provided on the top surface of the head lamp cap body, the head lamp body it will be hit first when a heavy object falls. And the hit will cause the failure or sparks of the circuit inside the head lamp body, which will in turn lead to a risk of explosion when the gas concentration reached the explosion point.